8 



5. 





30. 



9 



10. 





30. 



10 



10. 



11 



10. 



12 



10. 





20. 



Notes to the Extra Observations of Magnetometers, February 5 — 7, 1845. 121 



NOTES ON THE AURORA BOREALES SEEN AT MAKERSTOUN. 



The appearance, as noted at 9™, was mucli the same as if sheets of the very thinnest vapoury haze 

 had been suddenly illuminated by a rising moon. The stars were as well defined in the aurora 

 as in the dark spaces unoccupied by it, the only difference consisting in the ground on which they 

 were seen. The moon did not rise for several hours after this, but there was not the slightest 

 doubt as to the auroral character of the phenomenon. (B .) 



[All the remarks on aurora are given almost verbatim as they were noted during the phenomena. 

 The above is a description of a phenomenon which I have named milky aurora, interesting for its 

 peculiar character. It was observed on this occasion for the first time, but has been several times 

 observed since, and always during very minute magnetic irregularities ; in several instances it 

 covered the sky uniformly, giving an unusual degree of luminosity to a starlight night. One 

 distinctive difference between this appearance and that of thin cirrous haze, is the clear definition 

 of the stars ; stars within the ordinary phenomenon of auroral sheets are seen exactly as if ob- 

 served through a telescope with an illuminated field ; this is the case during milky aurora ; in 

 haze, however, the stars become blurred even when the haze is thinnest. October 1848. B.] 

 eb. 5 8 5. Bank of auroral light to NNW. like strong twilight. 



Aurora brighter, and extending rather higher. 



Aixroral light in form of a segment of a circle, summit of the arch in the astronomical meridian. 



As before. 



Aurora quite steady, not so bright as last hour. 



Faint auroral light behind the clouds to N. 



Faint aurora in form of an arch, altitude 5°, crown in the magnetic meridian. 



Arch measured, azimuths of extremities N. 27^° E. and N. 67° W., centre of arch N. 20° W., altitude 

 of summit 8°. 

 38. Streamers shooting out from the arch all along. 44™. Streamers fainter and fewer ; one rather 



bright to NNE. 

 45 — 50. A low auroral arch, quite black below, with bright persistent streamers to (WNW. ?) The sky 



decidedly blacker immediately without the arch than at a distance from it. 

 49. One very vivid pencil to NW. moving eastward, disappeared before 51™. 



64. A bundle of pencils to NW. moving E., no other pencils along the arch. 57™. Arch faint, several 

 streamers breaking out in all parts of it. 

 13 4. Aurora altogether much fainter, one or two very faint streamers. 11™. Aurora brighter; patches close 

 on horizon, like the tops of streamers from a lower arch ; arch broken up into pencils to NW., a 

 black streak of cirro-stratus there. 14™. Arch quite broken ; a number of bundles of pencils ; 

 streak of cii'ro-stratus still to NW. ; shooting star to N., altitude 30°, moving towards N. horizon. 

 19™. The streak of cloud has disappeared ; aurora quite amorphous, and much diminished in alti- 

 tude ; masses of streamers interpsersed, none of them bright. 24™. Aurora fainter, a great 

 number of very faint streamers. 29™. Much as before, several small patches of cloud near N. 

 horizon ; after this the aurora gradually became fainter, and at 50™ could scarcely be distinguished. 

 The greatest altitude of the arch did not exceed 12°. The previous observations after lO'' 10™ 

 were made by Mr Welsh at the Observatory ; the following were made by myself at my own 

 residence, about 300 yards from the Observatory. 

 13 10 — 15. Arch as before, altitude not above 6° or 7°, no streamer at 10™, black within the arch, afterwards 

 streamers from the same point as before, and, within the black, others rise all along the horizon ; 

 they shew what I could not observe before, several small black patches of (cirro-stratus 1) within 

 the black to (NW. "?) the blackish sky without the arch extends to 45° altitude, and is blackest in one 

 point. This cannot be a deception due to the effect of the adjacent light on the eye, since, when 

 the aurora is shut out from view, the blackness still subsists as before. The stars seem duller, 

 as if covered by a thin cloud in the black. The darkness seems however greater and more ex- 

 tended when the brightness of the streamers is greatest. The form of the external blacloiess is 

 much that of the arch, but, as mentioned, extends farthest beside the bright streamers. I do not 

 remember to have observed this blackness so decided on any previous occasion. A shooting star 

 was seen about 12'' 46™, and another about 18^ 12™, both moving rapidly (B.) See notes on rosy 

 beams seen at sunrise lying nearly in the magnetic meridian. Meteorological Notes, Feb. 5*^ 20''. 

 eb. 7 14 5. Cirrous clouds like cirrous haze cover the greater part of the sky, rendering the stars dim, especially 

 to S. 

 10. On a more careful examination the sky seems covered with the milky aurora, as seen on February 

 1st, thick cirrous haze obscures the stars to altitude of 45° from S. ; they become more and more 

 distinct to zenith, where the appearance is milky. Faint Pulsations 1 



MAG. AND MET. OBS. 1845. 2 H 



